Flood risk assessments, with local knowledge

Unda provides flood risk assessments and drainage strategies for sites across England and Wales. For every location we bring detailed local knowledge — the rivers and catchments, the history of flooding, and the planning and drainage policy each council applies — so your assessment reflects how flood risk actually behaves there.

Wherever you’re building in England and Wales, that local depth comes as standard. Explore a published local guide below, or start a quote and one of our experienced flood risk consultants will talk through your site.

Flood risk is local: the same scheme can face very different requirements depending on its river catchment, the council’s drainage standards and the flood zones mapped around it.

Find your area

Search a postcode, town or city to drop a pin on the map. Where a published local guide matches the site, we’ll show it. Otherwise, we’ll show the nearest relevant guides or route you to a quote.

Browse flood risk assessments by area

Prefer to browse? The areas below are grouped by region. Each county is listed first, with the towns and cities within it beneath.

Flood risk assessments for every situation

People come to us for a flood risk assessment for many reasons — securing planning permission, buying a home, satisfying a mortgage lender or insurer, achieving a BREEAM rating, or designing the drainage for a new scheme. We prepare the right report for each.

It helps to keep three things separate: a flood risk assessment, a sequential or exception test, and a drainage strategy are three distinct reports. They often travel together in a planning submission, but they answer different questions — is the site safe, should the development be here, and where does the surface water go. Groundwater and flood modelling aren’t separate reports: groundwater is a source every assessment considers, and modelling is a technique that feeds one.

• Flood risk assessment for planning. The site-specific report that satisfies the NPPF in England, or TAN15 in Wales, and shows your development is safe for its lifetime without increasing risk elsewhere.
• Flood consequence assessment (Wales). The TAN15 assessment for Welsh sites, demonstrating the consequences of flooding can be safely managed over the development’s lifetime.
• Flood risk survey for property purchase. An independent, property-specific survey for buyers and their advisers, going beyond the conveyancing search to assess the actual building.
• Flood risk assessment for insurance. Property-level evidence for brokers and underwriters where cover has been restricted, declined or priced on flood risk.
• Flood risk assessment for BREEAM. Structured around BREEAM Pol 03 so a scheme keeps its flood and surface-water credits.
• Sequential and exception tests. The locational justification that a higher-risk site is the most appropriate available, prepared alongside the assessment.
• Groundwater flood risk. A defensible design groundwater level, tested against floor levels, basements and drainage.
• Flood modelling. 1D and 2D hydraulic modelling for sites where national mapping doesn’t reflect how water actually behaves on the ground.
• Surface-water drainage strategy (SuDS). A scheme that manages runoff to the local SuDS standard, following the four pillars of SuDS and the drainage hierarchy.
• Discharge of drainage conditions. The detailed design that discharges a pre-commencement or pre-occupation drainage condition on a permission.